DE 100 26 700 A1 discloses an analysis method for an image data record which features a multiplicity of image data elements, wherein each image data element is assigned a position in a two-dimensional area and each image data element features an image data value. A computer, using an assignment rule which is based on the image data values of the image data elements of the image data record, divides the image data record into an empty region and a complementary signal region. By virtue of the manner in which the signal region is determined, the signal region is a closed outline. At the same time, it corresponds to an analysis region in which the image data record is analyzed.
Analysis methods for image data records of an examination object—often a human being—are used in many applications, inter alia the analysis of medical images. A typical example of a medical application relates to image data records showing blood vessels and tissues which are supplied by the blood vessels, wherein a contrast means is injected into the blood. Such image data records are used e.g. in the case of angiographic examinations of the human brain or the human heart.
In the simplest case, the image data records are output to an operator (e.g. a doctor).
In a multiplicity of cases, however, a computer carries out analyses of the image data records. On the basis of a chronological sequence of the image data records, for example, the computer can perform a perfusion analysis of the tissue which is supplied with blood. On the basis of an analysis of the chronological sequence of the image data records, for example, it is also possible to specify a flow speed of the blood in the vessels.
It is possible for the analysis—designated as “further analysis” in the present invention—to be carried out in the whole image data records. This approach has the advantage of being relatively simple. However, it has the disadvantage that the analysis is often carried out to a considerable extent in regions of the image data records which are irrelevant with regard to the desired analysis. The disadvantage is even more serious because the analysis is often very computer-intensive and medical emergencies are concerned in many cases. In the context of emergency medical assistance, however, minutes or even several seconds can decide between life and death in individual cases.
It is also possible for the operator to preset an analysis region (often designated as ROI=region of interest) for the computer, and for the computer to restrict the analysis to the analysis region. This approach already represents an improvement, because the time-intensive analysis now only needs to be carried out in the analysis region. However, serious disadvantages remain or now arise as a result of this approach.
For example, time is required for the presetting of the analysis region, such that the time saving is suboptimal. This applies in particular if the operator must preset a separate analysis region for each image data record or if the presetting of the analysis region is difficult, e.g. because the required analysis region can only be specified on the basis of the totality of the image data records. Furthermore, the presetting of the analysis region by the operator is susceptible to error and often suboptimal. This applies in particular if the operator is relatively inexperienced. The presetting also places a physical or psychological stress on the operator.